Isolation and Characterization of Lytic Bacteriophages of E.coli from Anzali Lagoon

Background and Aim : Escherichia coli (E. coli) is a Gram-negative, facultative anaerobicBacillus, whose pathogenic strains are responsible for some infections of the digestive, urinary,pulmonary, and neurotic systems. They are among the most common causes of septicemia in mosthospitals. On the other hand, the rapid spread of antibiotic resistance to bacterial pathogens in theworld has led to many research to discover new antimicrobial agents. The use of the antibacterialpotential and specific function of bacteriophages is one of the most important ones. In this research,an attempt was made to extract and identify phage(s) from a source with high probability ofcontaining this bacterium (Anzali lagoon) that have an effect on E. coli.Methods : Several water samples were collected from different places of the lagoon. Each samplewas passed through sterile filters of ۰.۲۲μm and ۰.۴۵μm after centrifugation. The presence of lyticphage (s) were investigated by plaque formation assay on double-layer Luria-Bertani (LB) agarmedium containing bacteria E. coli. Then, serial dilutions were prepared from each of the moretransparent and distinct plaques that indicated the possibility of the presence of at least one type ofphage. For further purification, the steps of filtration and culture on double-layer agar and plaqueformation were repeated until obtaining a specific plaque in relatively same shape and size. At theend, the representative samples were imaged by TEM electron microscope after negative stainingon Grid-Formvar/Carbon Coated.Results : ۳ types of lytic phages which were effective on E. coli were identified in the images.They probably belong to the Myoviridae family based on the reference size and shape.Conclusion : ۳ types of isolated phages as specific antimicrobial agents of E. coli bacteria can beused individually or as cocktails.

کلیدواژه ها:

Lytic bacteriophages ، E. coli ، Phage therapy ، Antibiotic resistance